Calcium L-Lactate Frameworks as Naturally Degradable Carriers

ABSTRACT

Porous calcium lactate metal-organic frameworks (MOFs) comprise non-toxic metal ions—Ca(II) and non-toxic, renewable and cheap linkers—lactate and acetate. The MOFs are nontoxic and environmentally-benign, and can be used as degradable carriers.

INTRODUCTION

Metalorganic frameworks (MOFs) are porous, crystalline materialsconstructed by linking metal ions with organic structs.¹ The diversenumber of ways the size, geometry, and functionality of the organicstruts and the metal ions can be tuned has led to the discovery of morethan 20,000 MOFs,² which allows a wide range of applications, mostnotably in gas separation, storage, and catalysis.³ However, the vastmajority of MOFs that have been made so far are based on transitionmetal ions and organic linkers derived from petrochemical sources, theirintrinsic toxicity has precluded many of the important applicationsrequiring eco-friendly (environment-friendly) materials, e.g. foodindustry, biomedical application, and agriculture.⁴

Preparation of MOFs from eco-friendly metal ions—Ca²⁺, with non-toxic,naturally occurring linkers would permit these wider scopeapplications.^(4,5) Though lots of attention have been focused on thearea, no porous examples have been demonstrated to date. The challengelies in both of the components: the poorly-defined coordinationgeometries and high coordination number of Ca²⁺ metal ions, and theflexibility of naturally occurring organic linkers, which generally leadto dense structures.^(4,6)

SUMMARY OF THE INVENTION

Disclosed are porous calcium lactate metal-organic frameworks (MOFs),made from non-toxic metal ions—Ca(II) and non-toxic, renewable and cheaplinkers—lactate and acetate. The MOFs are environmentally-benign, and wedemonstrate their use as a degradable solid carriers, including forpesticides, like volatile fumigants, showing that the MOFS not onlyprolong the effective time of the fumigants through slow release, butalso degrade easily after implementation, leaving only fertilizer (Ca)in the soil.

In aspect the invention provides a Ca²⁺-based metal-organic framework(MOF) composition comprising chelating L-lactate and acetate, offormula:

[Ca₁₄(L-lactate)(₁₆₋₂₄) (Acetate)(₁₂₋₄)] or [Ca₆(L-lactate)(₂₋₄)(Acetate)(₁₀₋₈)],

wherein the lactate and acetate sum to 28 and 12, respectively.

In embodiments the invention provides:

-   -   the formula is: [Ca₁₄(L-lactate)(₁₈) (Acetate)(₁₀₎],        [Ca₁₄(L-lactate)(₂₁₎ (Acetate)(₇)], [Ca₆(L-lactate)(₄)        (Acetate)(₈)], or [Ca₆(L-lactate)(_(2.5)) (Acetate)(_(9.5))];    -   the MOF is MOF-1201 of formula: [Ca₁₄(L-lactate)(₂₀)        (Acetate)(₈)];    -   the MOF is MOF-1203 of formula: [Ca₆(L-lactate)(₃)        (Acetate)(₉)];    -   the composition comprises an agent encapsulated in the MOF, such        as wherein the agent is selected from:

a crop protection product, such as a fertilizer (e.g. nitrogenous,phosphate, potassium, or calcium fertilizer) or pesticide (e.g.insecticide, herbicide, fungicide), which may be a fumigant or sprayableformulation;

a drug or therapeutic agent, such as an antimicrobial (e.g.antibacterial, antiviral or antifungal) agent, dermatological or skin orhair care agent, etc.

an aroma compound, such as an odorant, aroma, fragrance or perfumeincluding essential oil, extracts, synthetic odorants; and

a food additive, such as acidulents and acidity regulators, anticakingagents, antifoaming and foaming agents, antioxidants like ascorbic acid,colorings and color retention agents, fortifying agents like vitamins,minerals, and micronutrients, emulsifiers, flavorings and flavorenhancers, glazing agents, preservatives, stabilizers, thickeners andgelling agents, natural and artificial sweeteners and thickeners.

In an aspect the invention provides a method of delivering ordistributing an agent in a non-toxic, biodegradable carrier, the methodcomprising delivering or distributing the agent encapsulated in asubject composition.

The invention encompasses all combination of the particular embodimentsrecited herein, as if each combination had been laboriously recited.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a. All distinct Ca²⁺ centers exist in MOF-1201 and theircoordination with lactate and acetate. Coordination numbers for Ca(1) toCa(14) are 8, 7, 6, 7, 9, 8, 7, 7, 7, 7, 8, 7, 7, and 6, respectively.

FIG. 1 b. All distinct Ca²⁺ centers exist in MOF-1203 and theircoordination with lactate and acetate. Coordination numbers for Ca(1) toCa(6) are 7, 8, 7, 8, 7, and 9, respectively.

FIG. 1 c. Coordination modes of the lactate [(i)-(vi)] and acetate[(vii)-(xi)]. C in black, O in red, Ca in cyan, Ca²⁺ oxide polyhedra incyan, H omitted for clarity.

FIG. 2a . Left column: asymmetric unit in MOF-1201 as shown inball-and-stick diagram; second column: overall structures viewed along baxis represented in calcium oxide polyhedral; right column, channelsviewed along b axis (top) and a axis (bottom).

FIG. 2b . First column: asymmetric unit in MOF-1203 as shown inball-and-stick diagram; second column: overall structures viewed along aaxis represented in calcium oxide polyhedra; right column, channelsviewed along a axis (top) and [011] direction (bottom).

FIG. 3a . Nitrogen sorption isotherms of MOF-1201 and 1203 at 77 K,solid and open circles represent the adsorption and desorption branches,respectively.

FIG. 3b . Powder X-ray patterns of activated (solvent-free) MOF-1201 and1203 samples compared with the simulated patterns from single crystalstructures.

FIG. 3c . cis-1,3-dichloropropene vapor adsorption isotherm in MOF-1201at 25° C., solid and open circles represent the adsorption anddesorption branches, respectively.

FIG. 3d . Slow release traces of pure liquid and MOF-1201 encapsulatedcis-1,3-dichloropropene at 25° C.

FIG. 4. Asymmetric unit in the single-crystal structure of MOF-1201(thermal ellipsoids with 30% probability). Hydrogen atoms are omittedfor clarity. Color scheme: C, grey; O, red; Ca, blue.

FIG. 5. Asymmetric unit in the single-crystal structure of MOF-1203(thermal ellipsoids with 30% probability). Hydrogen atoms are omittedfor clarity. Color scheme: C, grey; O, red; Ca, blue.

FIG. 6. Comparison of the experimental PXRD patterns of MOF-1201:activated (red) and simulated pattern (blue) from single crystal X-raydata.

FIG. 7. Comparison of the experimental PXRD patterns of MOF-1203:activated (red) and simulated pattern (blue) from single crystal X-raydata.

FIG. 8. TGA trace for the activated sample of MOF-1201 in air.

FIG. 9. TGA trace for the activated sample of MOF-1203 in air.

FIG. 10. ¹H-NMR spectrum of solution of MOF1201.

FIG. 11. ¹H-NMR spectrum of solution of MOF-1203.

FIG. 12. Multiple point BET plot of MOF-1201 giving a specific surfacearea of 430 m²/g.

FIG. 13. Multiple point BET plot of MOF-1203 giving a specific surfacearea of 162 m²/g.

DESCRIPTION OF PARTICULAR EMBODIMENTS OF THE INVENTION

Unless contraindicated or noted otherwise, in these descriptions andthroughout this specification, the terms “a” and “an” mean one or more,the term “or” means and/or and polypeptide sequences are understood toencompass opposite strands as well as alternative backbones describedherein.

It is understood that the examples and embodiments described herein arefor illustrative purposes only and that various modifications or changesin light thereof will be suggested to persons skilled in the art and areto be included within the spirit and purview of this application andscope of the appended claims. All publications, patents, and patentapplications cited herein, including citations therein, are herebyincorporated by reference in their entirety for all purposes.

We exemplify the synthesis of eco-friendly MOFs including: MOF-1201[Ca₁₄(L-lactate)₂₀(Acetate)₈(C₂H₅OH)(H₂O)] and MOF-1203[Ca₆(L-lactate)₃(Acetate)₉(H₂O)], based on Ca²⁺ ions and innocuouslactate and acetate linkers,⁷ both show permanent porosity. We suspectthe key to our success in assembling MOF-1201 and 1203 lies in thechoice of linkers—the chelating lactate and acetate, which allows theformation of rigid calcium oxide linked polyhedra (Ca²⁺ as nodes and Ofrom lactate or acetate as bridges), and then the construction of 3Dextended open frameworks based on these polyhedra. We also demonstrateusing the MOFs as carriers, e.g. for the slow release of fumigantcis-1,3-dichloropropene. The ready degradability provides first examplesof porous carriers for fumigants that can decompose in water.

Hydrothermal reaction of a suspension of calcium acetate and L-lacticacid in ethanol (methanol) at 120° C. (100° C.) for a period of 4 (3)days gave colorless rod-shaped crystals of MOF-1201 (needle-shapedcrystals of MOF-1203), respectively. The crystals were then harvestedfor single-crystal X-ray diffraction analysis. The exact molar ratios ofthe lactate and acetate linkers in the MOFs were further determined by¹H-NMR spectroscopy and elemental microanalysis of the solvent-freesamples [see the Supporting Information (SI), section S1].

Single-crystal X-ray diffraction analysis revealed that both MOF-1201and 1203 are extended frameworks constructed from Ca²⁺ as nodes andlactate and acetate as linkers. MOF-1201 crystallizes in the monoclinicP2₁ space group with the lattice constant of a=24.39 Å, b=13.26 Å,c=24.97 Å, β=90.33°. In this structure, fourteen crystallographicallyunique calcium atoms exist [Ca(1) to Ca(14)] (FIG. 1a ), all of whichare capped by the O atoms from lactate (carboxylic O or hydroxyl O),acetate (carboxylic O) or water to form calcium oxide polyhedra.Coordination modes of the linkers vary across metal centers—fourdifferent modes are found in lactate [(i), (ii), (iii), and (vi)] andthree in acetate [(vii), (ix), and (xi)] (FIG. 1c ), among which thelactate with mode (vi) and the acetate with mode (vii) act as terminalligands and cap only one Ca²⁺ center [Ca(5), and Ca(11), respectively],whilst others act as bridges to connect two or three Ca²⁺. In theasymmetric unit, Ca(1), Ca(2), and Ca(3) are bridged by a lactate withcoordination mode (i)—Ca(1) coordinates to the hydroxyl O and theadjacent carboxylic O, Ca(2) coordinates to only the carboxylic O, andCa(3) coordinates to the other carboxylic O (FIG. 2a , left column)Similarly, Ca(1), Ca(2), and Ca(4) are bridged by the same mode; Ca(4),Ca(5), and Ca(7) are bridged by mode (iii); Ca(7), Ca(8), and Ca(9) bymode (i); Ca(7), Ca(8), and Ca(10) by mode (i); Ca(10), Ca(11), andCa(12) by mode (xi); Ca(6), Ca(5), and Ca(7) by mode (ii); Ca(6),Ca(13), and Ca(14) by mode (i) to connect all of the Ca²⁺ centers.

The resultant extended framework of MOF-1201 possesses 1D infinitechannels along b axis (FIG. 2a , middle column) The channels areconstructed from a right-handed single strand helical chain (FIG. 2a ,right column), with sixteen Ca²⁺ atoms per turn [in the sequence ofCa(4), Ca(2), Ca(1), Ca(11), Ca(12), Ca(13), Ca(6), Ca(5), Ca(4), Ca(2),Ca(1), Ca(11), Ca(12), Ca(13), Ca(6), and Ca(5)]. The aperture is around7.8 Å and the pitch is around 13.3 Å. Two adjacent turns are furthercrosslinked by extra calcium oxide polyhedra. Specifically, the twoCa(2) and two Ca(13) centers in each turn are bridged by three calciumoxide polyhedra (in the sequence of Ca(3)-Ca(2)-Ca(3), andCa(14)-Ca(13)-Ca(14)). The two Ca(5) and two Ca(11) in each turn arebridged by seven calcium oxide polyhedra [in the sequence ofCa(7)-Ca(8)-Ca(9)-Ca(8)-Ca(9)-Ca(8)-Ca(7), andCa(10)-Ca(8)-Ca(9)-Ca(8)-Ca(9)-Ca(8)-Ca(10)]. The curved bridges resultin a slightly larger internal pore size (c.a. 9.6 Å) compared to theaperture.

In FIG. 2a first column the asymmetric unit in MOF-1201 is shown in aball-and-stick diagram, ligands who partially connect to symmetrygenerated Ca²⁺ centers are omitted for clarity; more than one bridgecould exist for the same set of Ca²⁺ centers; second column overallstructures viewed along b axis represented in calcium oxide polyhedra.Asymmetric units are highlighted, and open channels are shown; rightcolumn, channels viewed along b axis (top) and a axis (bottom). Calciumoxide polyhedra belonging to aperture are highlighted. In color, asshown in priority application, C in black, O in red, Ca in cyan, Ca²⁺oxide polyhedra in cyan, H omitted for clarity.

The other MOF-1203, crystallized in the orthorhombic I2₁2₁2₁ spacegroup, has a lattice constant of a=10.50 Å, b=22.26 Å, c=31.25 Å. Sixdistinct Ca²⁺ centers exist in the structure, and are linked by lactateand acetate to form linked calcium oxide polyhedra (FIG. 1b ). Threecoordination modes are found in lactate [(i), (iv), and (v)] and inacetate [(viii), (x), and (xi)] (FIG. 1c ), all linkers act as bridgesconnecting two to four Ca²⁺ centers. In the asymmetric unit, Ca(1),Ca(2), Ca(3), and Ca(6) are bridged by a lactate with coordination mode(iv)—Ca(6) coordinates to the hydroxyl O and the adjacent carboxylic O,Ca(1) coordinates to only the carboxylic O, and Ca(2) and Ca(3)coordinate to the other carboxylic O (FIG. 2b , left column) Ca(3),Ca(4), and Ca(5) are bridged by an acetate with mode (xi). The resultantextended framework reveals another type of 1D open channel, which has anaperture made from 22 calcium oxide polyhedra. However, the aperturesize is smaller than MOF-1201 as the result of its rectangular shape,and the two incurvate Ca(4) further divided the aperture into twosmaller ones (c.a. 4.6 Å).

In FIG. 2b first column: asymmetric unit in MOF-1203 as shown inball-and-stick diagram, ligands who partially connect to symmetrygenerated Ca²⁺ centers are omitted for clarity; more than one bridgecould exist for the same set of Ca²⁺ centers; second column overallstructures viewed along a axis represented in calcium oxide polyhedra.Asymmetric units are highlighted, and open channels are shown; rightcolumn, channels viewed along a axis (top) and [011] direction (bottom).Calcium oxide polyhedra belonging to aperture are highlighted. In color,as shown in priority application, C in black, O in red, Ca in cyan, Ca²⁺oxide polyhedra in cyan, H omitted for clarity

Samples of MOF-1201 and MOF-1203 were solvent exchanged with ethanol(MOF-1201) and methanol (MOF-1203) for three days, followed by directevacuation under dynamic vacuum (0.04 mbar) at room temperature for 12hours to give solvent-free samples for the examination of the permanentporosity. Nitrogen sorption measurements at 77 K were then carried out.Both of the frameworks exhibited a fully reversible type I isotherm withsteep N₂ uptake in the low-pressure regions (P/P₀<0.05) (FIG. 3a ),indicating the permanent microporosity of these materials.⁸ TheBrunauer-Emmett-Teller (BET) surface areas⁹ of MOF-1201 and MOF-1203 areestimated to be 430 and 160 m² g⁻¹ from N₂ isotherms. They possess porevolumes of 0.18 cm³ g⁻¹ and 0.06 cm³ g⁻¹, respectively, which are thesame as those calculated from single crystal structures using PLATON.¹⁹Crystallinity of the solvent-free samples were then checked with powderX-ray diffraction (PXRD). The obtained powder patterns are in goodagreement with the diffraction patterns simulated from the singlecrystal structures, confirming structural integrity upon activation andthe phase purity of the bulk materials (FIG. 3b , FIGS. 6-7).

The porosity of MOF-1201 along with its eco-friendly compositions: Ca²⁺,lactate, and acetate, allowed us to explore the potential application ofmetal-organic framework materials in agriculture and food industry,where the non-toxicity and human and environmental benignity are themost important requirements for a material to be used.^(4,5) Here we'vedemonstrated the use of MOF-1201 as a solid formulation for volatileliquid fumigants.

Fumigants are one of the most important family of pesticides, which arewidely used to prevent plants, especially these of high-value (e.g.strawberries and tomatoes), from soil-borne diseases to improve thequality and yield.¹¹ Two volatile liquid compounds, 1,3-dichloropropene(cis- and trans-mixtures) and chloropicrin, have been the most widelyused fumigants with a large quantity being consumed each year.¹¹⁻¹²Indeed, a pesticide use report published by California Department ofPesticide Regulations (CDPR) indicates the use of 1,3-dichloropropeneand chloropicrin have achieved 5.99×10⁶ kg and 4.08×10⁶ kg respectivelyin California in 2014, ranking the 3^(rd) and 5^(th) of the allpesticides being used.¹³

Commercial formulations for the 1,3-dichloropropene or chloropicrin relyon the liquid forms (Telone®) applied by shank injection or by dripirrigation.¹⁴ However, the direct use of liquids requires high dosage,which causes substantial air and groundwater pollution due to the highvolatility and mobility of the liquid chemicals, as well as significantsafety hazards to workers during handling and transporting.^(11, 14-15)As a result of these adverse effects, the use of these chemicals arehighly regulated, with both personal protective equipment and a bufferzone required.

Sorption based formulations using porous solids to adsorp fumigants andthen slow release have emerged as an alternative to suppress thevolatility, and toxicity of the chemicals as well as reducepollutions.¹⁶ Porous matrices such as activated carbon, activated clay,adsorption resin, and activated alumina have been proposed and shownprolonged effective lifetime of fumigants,¹⁶ however, none of thesecarrier materials are naturally degradable, which greatly increasestheir environmental impact due to accumulation after implementation.

Here we present the use of MOF-1201 for this purpose Fumigantcis-1,3-dichloropropene has been chosen as an example. Static adsorptionisotherm of cis-1,3-dichloropropene in MOF-1201 at 25° C. is shown inFIG. 3c , displaying a sharp uptake of 1.4 mmol g⁻¹ (13 wt %) in lowpartial pressure range (P/P₀=0.1), attributed to adsorption within themicropores. This uptake was in the range of the values achieved in otherporous materials (5-40 wt %).^(16d) Preliminary slow release performancewas demonstrated in lab by purging the sample of cis-1,3-dichloropropeneloaded MOF-1201 or liquid cis-1,3-dichloropropene in an air flow of 1.0cm³ min⁻¹ and the sample weight was monitored by thermogravimetricinstrument. As shown in FIG. 3d , liquid cis-1,3-dichloropropenereleased quickly, with 80% of the total weight evaporated within 1,000min g⁻¹. In contrast, the cis-1,3-dichloropropene encapsulated inMOF-1201 released in a much slower manner, with 80% of the total (10.5wt %) released in 100,000 min g⁻¹, corresponding to 100 times slowercompared with liquid cis-1,3-dichloropropene under the same conditions.

The degradability of MOF-1201 was then tested. MOF-1201 can be easilydissolved in water to give its eco-friendly components: Ca²⁺ ions,lactate, and acetate (FIG. 10). It is found that 1 L water can dissolve120±10 g of MOF-1201, and the saturated solution has a nearly neutral pHvalue (7.6). This property allows MOF-1201 the potential to overcome theaccumulation issues within other porous materials, thus minimize adverseeffects to the environment but leaving fertilizer (calcium) to thesoil.¹⁷

To conclude, we have demonstrated the first examples of eco-friendlyCa²⁺ MOFs constructed from non-toxic, renewable lactate linkers. Wefurther demonstrated the use of MOF-1201 as a degradable carriers. Ourresults demonstrate both the creation of eco-friendly Ca MOFs and theiruse in agriculture.

REFERENCES

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SYNTHETIC PROCEDURES

Calcium acetate monohydrate (Ca(OAc)₂H₂O), L-(+)-Lactic acid, anhydrousmethanol and ethanol were purchased from commercial source and were useddirectly without further purification. All the synthetic procedures wereconducted in air. The MOFs were activated by the following procedure:As-synthesized MOFs were washed with fresh anhydrous ethanol (MOF-1201)and methanol (MOF-1203) for 1 day, six times per day. The samples werethen evacuated to remove guest molecules under vacuum (0.01 Torr) atambient temperature for 12 hrs. The following measurements wereconducted using the activated samples for MOFs unless otherwise noted.

Elemental analysis (EA) of activated MOF-1201 and -3 were performedusing a Perkin Elmer 2400 Series II CHNS elemental analyzer; ¹H NMRspectra on digested solutions of MOFs were acquired on a Bruker AVB-400NMR spectrometer, with chemical shifts of linkers identified bycomparing with spectra for each pure linker. Samples (ca. 10 mg foreach) were dissolved in D₂O (600 μL) with sonication;Attenuated-total-reflectance Fourier-transform infrared (ATR-FTIR)spectra of neat ZIFs were recorded on a Bruker ALPHA Platinum ATR-FTIRSpectrometer.

MOF-1201, Ca₁₄(L-lactate)₂₀(Acetate)₈(EtOH)(H₂O). 0.071 g calciumacetate monohydrate (Ca(OAc)₂H₂O, 0.4 mmol), and 0.072 g L-(+)-Lacticacid (HL, 0.8 mmol) were mixed in 6 mL anhydrous ethanol in a 23 mLTeflon autoclave. The autoclave was then sealed and heated in 120° C.isothermal oven for 4 days. After cooling down to room temperature, thecrystals were washed with anhydrous ethanol for 1 day. (Yield: 26% basedon Ca). EA: Calcd. for Ca₁₄(C₃H₅O₃)₂₀(C₂H₃O₂)₈(C₂H₆O)(H₂O): C, 32.54; H,4.62. Found: C, 31.67; H, 4.75. ATR-FTIR (4000-400 cm⁻¹): 3250(br),2979(w), 1563(s), 1422(s), 1314(m), 1267(m), 1122(s), 1089(w), 1044(m),930(w), 858(m), 773(m), 664(m), 616(m), 550(m), 469(w), 442(w), 423(w).

MOF-1203, Ca₆(L-lactate)₃(Acetate)₉(H₂O). 0.071 g calcium acetatemonohydrate (Ca(OAc)₂H₂O, 0.4 mmol), and 0.036 g L-(+)-Lactic acid (HL,0.4 mmol) were mixed in 6 mL anhydrous methanol in a 23 mL Teflonautoclave. The autoclave was then sealed and heated in 100° C.isothermal oven for 3 days. After cooling down to room temperature, thecrystals were washed with anhydrous methanol for 1 day. (Yield: 25%based on Ca). EA: Calcd. for Ca₆(C₃H₅O₃)₃(C₂H₃O₂)₉: C, 30.68; H, 4.20.Found: C, 31.33; H, 4.07. ATR-FTIR (4000-400 cm⁻¹): 3300(br), 2981(w),1540(s), 1462(s), 1417(s), 1320(w), 1271(m), 1138(m), 1123(m), 1051(w),1024(m), 956(w), 934(w), 860(m), 774(m), 662(s), 649(m), 617(s), 561(m),468(m), 419(w).

Single crystal X-ray diffraction (SXRD) data was collected for both MOFsusing as-synthesized crystals. Data for MOF-1201 and -3 were collectedat beamline 11.3.1 of the ALS at LBNL, equipped with a Bruker Photon 100CMOS area detector using synchrotron radiation (10-17 KeV), at 0.7749(1)Å. Samples were mounted on MiTeGen® kapton loops and placed in a 100(2)K nitrogen cold stream.

Data were processed with the Bruker APEX2 software package (AXS Inc.,Madison, Wis., 2010; Sheldrick, G. M. Acta Cryst. A 2008, 64, 112-122),integrated using SAINT v8.34A and corrected for the absorption by SADABS2014/4 routines (no correction was made for extinction or decay). Thestructures were solved by intrinsic phasing (SHELXT) and refined byfull-matrix least squares on F² (SHELXL-2014). All non-hydrogen atomswere refined anisotropically. Hydrogen atoms were geometricallycalculated and refined as riding atoms unless otherwise noted. In bothstructures, highly disordered guest molecules occupying the cavities ofthe structure, which could not be modeled and so were accounted forusing solvent masking using the Olex2 software package (Dolomanov, etal. Appl. Cryst. 2009, 42, 339-341; Rees, et al. Acta Cryst. D 2005, 61,1299-13); see the CIFs for further details.

MOF-1201. A colorless rod-shaped (100 μm×20 μm×20 μm) crystal ofas-synthesized MOF-1201 was quickly picked up from the mother liquor,and placed in paratone oil to minimize crystal degradation, and mountedat beamline 11.3.1 at the ALS using radiation at λ=0.7749(1) Å at 100 K.

TABLE S1 Crystal data and structure determination for MOF-1201 CompoundMOF-1201 Chemical formula C₇₆H₁₂₇O₇₆Ca₁₄ Formula mass 2817.89 Crystalsystem monoclinic Space group P2₁ λ (Å) 0.7749 (1) a (Å) 24.3868 (11) b(Å) 13.2612 (6) c (Å) 24.9710 (10) β (°) 90.327 (2) Z 2 V (Å³) 8075.4(6) Temperature (K) 100 (2) Size/mm³ 0.1 × 0.02 × 0.02 Density (g/cm⁻³)1.159 Measured reflections 119229 Unique reflections 29436 Parameters1544 Restraints 265 R_(int) 0.0723 θ range (°) 2.10-27.89 R₁, wR₂0.0621, 0.1772 S (GOF) 1.076 Max/min res. dens. (e/Å³) 0.60/−0.33 Flackparameter 0.150 (10) ^(a)R₁ = Σ||F_(o)| − |F_(c)||/Σ|F_(o)|; ^(b)wR₂ =[Σw(F_(o) ² − F_(c) ²)²/Σw(F_(o) ²)²]^(1/2); ^(c)S = [Σw(F_(o) ² − F_(c)²)²/(N_(ref) − N_(par))]^(1/2). MOF-1203. A colorless needle-shaped (90μm × 90 μm × 5 μm) crystal of as-synthesized MOF-1203 was quickly pickedup from the mother liquor and mounted at beamline 11.3.1 at the ALSusing radiation at λ = 0.7749 (1) Å.

TABLE S2 Crystal data and structure determination for MOF-1203 CompoundMOF-1203 Chemical formula C₄₀H_(59.33)O_(40.67)Ca₉ Formula mass 1551.64Crystal system orthorhombic Space group I2₁2₁2₁ λ (Å) 0.7749 (1) a (Å)10.5046 (4) b (Å) 22.2580 (9) c (Å) 31.2485 (13) Z 4 V (Å³) 7306.3 (5)Temperature (K) 100 (2) Size/mm³ 0.09 × 0.005 × 0.005 Density (g/cm⁻³)1.411 Measured reflections 7620 Unique reflections 3865 Parameters 433Restraints 59 R_(int) 0.1195 θ range (°) 2.23-22.86 R₁, wR₂ 0.0524,0.1406 S (GOF) 1.026 Max/min res. dens. (e/Å³) 0.60/−0.33 Flackparameter 0.09 (3) ^(a)R₁ = Σ||F_(o)| − |F_(c)||/Σ|F_(o)|; ^(b)wR₂ =[Σw(F_(o) ² − F_(c) ²)²/Σw(F_(o) ²)²]^(1/2); ^(c)S = [Σw(F_(o) ² − F_(c)²)²/(N_(ref) − N_(par))]^(1/2).

Powder X-ray diffraction (PXRD) analysis were conducted on a Bruker D8Advance diffractometer with Cu K_(α) radiation (λ=1.54056 Å). Phasepurity of the materials is examined by comparing experimental andsimulated PXRD patterns.

Thermogravimetric analysis (TGA) curves were recorded using a TA Q500thermal analysis system under air flow.

Fumigant adsorption and slow release measurements.cis-1,3-dichloropropene vapor sorption isotherm at 25° C. were measuredin-house on a BEL Japan BELSORP-aqua3. Prior to measurements, theanalyte was flash frozen in liquid nitrogen and then evacuated underdynamic vacuum at least twice to remove any gases from the reservoir.The measurement temperature was controlled and monitored with a waterbath held at 25° C. Helium was used to estimate dead space for vaporadsorption measurements.

Slow release experiments were carried out using the TA Q500 thermalanalysis system under constant air flow rate of 1 cm³ min ⁻¹.

1. A Ca²⁺-based metal-organic framework (MOF) composition comprisingchelating L-lactate and acetate, the MOF of formula:[Ca₁₄(L-lactate)(₁₆₋₂₄) (Acetate)(₁₂₋₄)] or [Ca₆(L-lactate)(₂₋₄)(acetate)(₁₀₋₈)], wherein the lactate and acetate sum to 28 and 12,respectively.
 2. The composition of claim 1, wherein the MOF is offormula: [Ca₁₄(L-lactate)(₁₆₋₂₄) (acetate)(₁₂-4)], wherein the lactateand acetate sum to
 28. 3. The composition of claim 1, wherein the MOF isof formula: [Ca₁₄(L-lactate)(₁₈) (acetate)(₁₉)].
 4. The composition ofclaim 1, wherein the MOF is of formula: [Ca₁₄(L-lactate)(₂₁)(acetate)(₇)].
 5. The composition of claim 1, wherein the MOF is offormula: [Ca₆(L-lactate)(₂₋₄) (acetate)(₁₀₋₈)], wherein the lactate andacetate sum to
 12. 6. The composition of claim 1, wherein the MOF is offormula: [Ca₆(L-lactate)(₄) (acetate)(₈)].
 7. The composition of claim1, wherein the MOF is of formula: [Ca₆(L-lactate)(₂ ₅)(acetate)(_(9.5))].
 8. The composition of claim 1 wherein the MOF isMOF-1201 of formula: [Ca₁₄(L-lactate)(₂₀) (acetate)(₈)].
 9. Thecomposition of claim 1 wherein the MOF is MOF-1203 of formula:[Ca₆(L-lactate)(₃) (acetate)(₉)].
 10. The composition of claim 1comprising an agent encapsulated in the MOF, wherein the agent is a cropprotection product selected from a fertilizer and a pesticide.
 11. Thecomposition of claim 1 comprising an agent encapsulated in the MOF,wherein the agent is a drug or a therapeutic agent selected from anantimicrobial agent, skin care agent and hair care agent.
 12. Thecomposition of claim 1 comprising an agent encapsulated in the MOF,wherein the agent is an aroma compound selected from an odorant, aroma,fragrance and perfume.
 13. The composition of claim 1 comprising anagent encapsulated in the MOF, wherein the agent is a food additiveselected from acidulents and acidity regulators, anticaking agents,antifoaming and foaming agents, antioxidants, colorings and colorretention agents, vitamins, minerals, and micronutrients, emulsifiers,flavorings and flavor enhancers, glazing agents, preservatives,stabilizers, thickeners and gelling agents, natural and artificialsweeteners and thickeners.
 14. The composition of claim 10 wherein theMOF is of formula selected from: [Ca₁₄(L-lactate)(₁₈) (acetate)(₁₀)],[Ca₁₄(L-lactate)(₂₁) (acetate)(₇)], [Ca₆(L-lactate)(₄) (acetate)(₈)],[Ca₆(L-lactate)(_(2.5)) (acetate)(_(9.5))], [Ca₁₄(L-lactate)(₂₀)(acetate)(₈)], and [Ca₆(L-lactate)(₃) (acetate)(₉)].
 15. The compositionof claim 11 wherein the MOF is of formula selected from:[Ca₁₄(L-lactate)(₁₈) (acetate)(₁₀)], [Ca₁₄(L-lactate)(₂₁) (acetate)(₇)],[Ca₆(L-lactate)(₄) (acetate)(₈)], [Ca₆(L-lactate)(_(2.5))(acetate)(_(9.5))], [Ca₁₄(L-lactate)(₂₀) (acetate)(₈)], and[Ca₆(L-lactate)(₃) (acetate)(₉)].
 16. The composition of claim 12wherein the MOF is of formula selected from: [Ca₁₄(L-lactate)(₁₈)(acetate)(₁₀)], [Ca₁₄(L-lactate)(₂₁) (acetate)(₇)], [Ca₆(L-lactate)(₄)(acetate)(₈)], [Ca₆(L-lactate)(_(2.5)) (acetate)(_(9.5))],[Ca₁₄(L-lactate)(₂₀) (acetate)(₈)], and [Ca₆(L-lactate)(₃)(acetate)(₉)].
 17. The composition of claim 13 wherein the MOF is offormula selected from: [Ca₁₄(L-lactate)(₁₈) (acetate)(₁₀)],[Ca₁₄(L-lactate)(₂₁) (acetate)(₇)], [Ca₆(L-lactate)(₄) (acetate)(₈)],[Ca₆(L-lactate)(_(2.5)) (acetate)(_(9.5))], [Ca₁₄(L-lactate)(₂₀)(acetate)(₈)], and [Ca₆(L-lactate)(₃) (acetate)(₉)].
 18. The compositionof claim 1 comprising a solid formulation of a volatile liquid fumigant,wherein the fumigant is encapsulated in the MOF and the MOF is MOF-1201of formula: [Ca₁₄(L-lactate)(₂₀) (acetate)(₈)].
 19. The composition ofclaim 1 comprising a solid formulation of a volatile liquid fumigant,wherein the fumigant is encapsulated in the MOF and the MOF is MOF-1203of formula: [Ca₆(L-lactate)(₃) (acetate)(₉)].
 20. A method of deliveringor distributing an agent in a non-toxic, biodegradable carrier, themethod comprising delivering or distributing the agent encapsulated inthe composition of claim 1.